Roadbed soil humidity automatic control system, design scheme generation method and medium

Abstract

The invention relates to the technical field of road engineering, in particular to an automatic subgrade soil humidity control system, a design scheme generation method and a medium, the system comprises a geotechnical composite layer, the geotechnical composite layer comprises a first composite layer, a second composite layer and a third composite layer, the first composite layer absorbs moisture of a subgrade soil body, and the second composite layer discharges moisture of the subgrade soil body; the third composite layer blocks underground capillary water; the collecting assembly is used for collecting roadbed soil humidity and external environment humidity; and the control assembly is used for carrying out humidity control operation on the geotechnical composite layer according to the roadbed soil body humidity and the external environment humidity so as to control the geotechnical composite layer to absorb or discharge moisture of the roadbed soil body. The system can automatically control the novel geotechnical composite layer to actively absorb and drain water to the roadbed soil body according to the humidity of the roadbed soil body and the humidity of the external environment, so that the humidity of the roadbed soil body is kept in a constant and safe state for a long time.

Description

Technical Field

[0001] The present application relates to the technical field of road engineering, and in particular to an automatic control system for roadbed soil moisture, a design scheme generation method, and a medium. Background Art

[0002] Fill roadbeds are a crucial component of road construction, and their performance is directly related to their moisture content (or humidity). This moisture content is primarily affected by the infiltration of rainfall and the rise in the groundwater level, including the resulting capillary water flow. Excessive moisture in the subgrade soil can lead to various roadbed diseases. Therefore, it is crucial to maintain the subgrade moisture content at a dry or moderately moist state.

[0003] Related technologies mainly use the following two methods to adjust the moisture state of the roadbed. One method is the traditional method of laying a crushed gravel cushion at the bottom of the base layer. This can quickly remove water seepage from the roadbed and effectively prevent the capillary rise of groundwater (underground saline-alkali water). However, in long-term operation, the pores of the crushed gravel are often clogged due to the deposition of fine particles, which significantly reduces its permeability. Another method is to use a geocomposite drainage layer with a mesh core in the middle and geotextiles attached to both sides of the mesh core to replace the crushed gravel cushion. However, this can only passively remove gravity water from the oversaturated roadbed soil, that is, the roadbed soil is still in a saturated state after drainage.

[0004] Current roadbed projects, especially low embankments or shallow cuttings with high groundwater levels, still lack a solution that can prevent siltation during the long-term service of the roadbed to maintain its good permeability and groundwater retention performance. Summary of the Invention

[0005] The present application provides an automatic control system for roadbed soil moisture, a design scheme generation method and a medium, which can automatically control the new geocomposite layer to actively absorb and drain the roadbed soil according to the moisture of both the roadbed soil and the external environment, so that the moisture of the roadbed soil can be maintained in a constant and safe state for a long time.

[0006] The first aspect of the present application provides an automatic control system for roadbed soil moisture, including: a geocomposite layer, wherein the geocomposite layer includes first to third composite layers, the first composite layer absorbs moisture from the roadbed soil, the second composite layer discharges moisture from the roadbed soil, and the third composite layer blocks underground capillary water; a collection component for collecting the moisture of the roadbed soil and the humidity of the external environment; a control component for performing humidity control operations on the geocomposite layer according to the humidity of the base soil and the humidity of the external environment to control the geocomposite layer to absorb or discharge moisture from the roadbed soil.

[0007] Optionally, the first composite layer is a gradient porosity wicking fiber geotextile layer, the second composite layer is a three-dimensional composite geonet layer, and the third composite layer is a geotextile layer.

[0008] Optionally, the geocomposite layer is laid horizontally along the roadbed as a whole, with both end portions directly exposed to the external environment or attached to the inner walls of the drainage ditches on both sides of the road shoulders. The pore equivalent aperture of the first composite layer is linearly proportional to the contact distance of the upper surface of the second composite layer. The pore equivalent aperture of the first composite layer close to both sides of the road shoulders is larger than the preset aperture. The second composite layer includes longitudinally arranged ribs in the middle and cross-arranged ribs in the upper and lower parts. The rigidity of the longitudinally arranged ribs in the middle is greater than the rigidity of the cross-arranged ribs in the upper and lower parts. The upper and lower surfaces of the second composite layer are covered with a third composite layer.

[0009] Optionally, the control component includes a ventilation device, a power output device and a controller, wherein the controller controls the ventilation device and the power output device to perform humidity control operations.

[0010] Optionally, the ventilation device includes a ventilation pipe, a vertical riser and a guide spiral wind hood, wherein the ventilation pipe is symmetrically laid on the roadbed soil near the road shoulder, the pipe body of the ventilation pipe is arranged in the first composite layer and the second composite layer, the pipe wall of the ventilation pipe is provided with wind holes distributed in a spiral shape, the vertical riser is connected to the horizontal ventilation pipe and is arranged perpendicular to the horizontal ventilation pipe, and the guide spiral wind hood, composed of guide blades and a top cap, is installed on the top of the vertical riser.

[0011] Optionally, the power output device includes an energy supply device, a pump case and an electric valve, wherein the energy supply device supplies energy to the pump case and the electric valve controls the ventilation speed of the pump case.

[0012] The second aspect of the present application provides a method for generating a design scheme for a geocomposite layer, which is used to generate a design scheme for the geocomposite layer in the roadbed soil moisture automatic control system of the above-mentioned embodiment, comprising the following steps: obtaining the environmental conditions of the roadbed soil, wherein the environmental conditions include the roadbed soil being in a saturated or unsaturated state, the roadbed soil being in an oversaturated state, and the capillary phenomenon of the roadbed soil; calculating the absorption, diffusion, and evaporation coupling efficiency of the first composite layer based on the roadbed soil being in a saturated or unsaturated state, calculating the drainage rate of the second composite layer based on the roadbed soil being in an oversaturated state, and calculating the blocking efficiency of the third composite layer based on the capillary phenomenon of the roadbed soil; determining the parameter range of the corresponding composite layer based on the absorption, diffusion, and evaporation coupling efficiency, the drainage rate, and the blocking efficiency, and generating a design scheme for the geocomposite layer based on the road engineering requirements and the parameter range.

[0013] Optionally, the calculation formula for the absorption-diffusion-evaporation coupling efficiency is:

[0014]

[0015] Among them, (ET) f is the absorption-diffusion-evaporation coupling rate, is the actual net radiation, G is the soil heat flux, ρ air is the air density, C p is the specific heat of air at constant pressure, e s is the temperature T air The saturated water vapor pressure of the air, e s is the temperature T air The actual water vapor pressure of the air at that time, is the equivalent aerodynamic impedance, λ is the latent heat of water vaporization, Δ is the slope of the saturated water vapor pressure curve, γ is the dry and wet constant, is the equivalent surface impedance, K ec is the absorption-diffusion-evaporation coupling coefficient;

[0016] The calculation formula for drainage rate is:

[0017]

[0018] in, is the drainage rate of the second composite layer, θ K is the hydraulic conductivity of the three-dimensional composite geonet, δ is the total thickness of the three-dimensional composite geonet, W is the longitudinal width of the geonet, δ1 and δ2 are the thickness of the main reinforcement and the secondary reinforcement respectively, s is the spacing of the equal-diameter reinforcements, is the included angle of the top projection of the primary and secondary reinforcement, θ net is the contact angle between the rib material and the transmission liquid infiltration interface, K P is the external load correction factor, K η is the material wettability correction factor;

[0019] The calculation formula for blocking efficiency is:

[0020]

[0021] Among them, η f is the retardation efficiency of the second composite layer, h 0-gd is the theoretical rising height of underground capillary water, h gd is the actual rising height of underground capillary water, θ net is the contact angle between the reinforcement material and the underground capillary water infiltration interface, f1 is the retardation correction constant, and δ is the actual thickness of the geonet.

[0022] A third aspect of the present application provides a computer-readable storage medium having a computer program or instructions stored thereon, which is executed by a processor to implement the method for generating a design scheme for a geocomposite layer as described in the above embodiment.

[0023] A fourth aspect of the present application provides a computer program. When the computer program is executed, it is used to implement the method for generating a design solution for a geocomposite layer as described in the above embodiment.

[0024] Therefore, this application has the following beneficial effects:

[0025] The embodiment of the present application constructs an automatic control system for roadbed soil moisture, including a geocomposite layer, a collection component and a control component. The control component can automatically control the geocomposite layer to absorb or remove moisture from the roadbed soil based on the roadbed soil moisture and external ambient temperature collected by the collection component, so as to ensure that the roadbed is in a stable and safe working state for a long time during its service.

[0026] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0028] Figure 1 Schematic diagram of an automatic control system for roadbed soil moisture according to an embodiment of the present application;

[0029] Figure 2 A schematic structural diagram of a resistive sensor provided according to an embodiment of the present application;

[0030] Figure 3 A structural diagram of a gradient porosity wicking fiber geotextile layer provided according to an embodiment of the present application;

[0031] Figure 4 Schematic diagram of the special-shaped cross-section structure of the wicking fiber provided according to an embodiment of the present application;

[0032] Figure 5 Schematic diagram of the cross section and planar structure of a three-dimensional composite geonet layer provided according to an embodiment of the present application;

[0033] Figure 6 A schematic diagram of a transverse cross-section of a geocomposite layer provided by an embodiment of the present application being laid along a roadbed;

[0034] Figure 7 A schematic diagram of the structure and laying method of a geocomposite layer provided according to an embodiment of the present application;

[0035] Figure 8 A schematic diagram of the structure of a control unit provided according to an embodiment of the present application;

[0036] Figure 9 A flow chart of a method for generating a design solution for a geocomposite layer according to an embodiment of the present application;

[0037] Figure 10The figure is a graph showing the relationship between the calculated values ​​and the experimental values ​​provided in the examples of the present application.

[0038] Description of reference numerals:

[0039] Surface layer 1, base layer 2, road base layer 3, ground base layer 4, groundwater 5, open drainage ditch 6, geocomposite layer 7, control unit 8, gradient pore wicking fiber geotextile 9, three-dimensional duplex geonet 10, non-woven geotextile 11, small pore wicking fiber layer 12, medium pore wicking fiber layer 13, large pore wicking fiber layer 14, special-shaped cross-section wicking fiber bundle 15, cross-section leaf 16, cross-section leaf root 17, cross-section leaf tip 18, main rib 19, secondary rib 20, drainage grid 21, Ventilation pipe 22, air hole 23, vertical riser 24, guide spiral hood 25, spiral guide vane 26, pump chassis 27, air pump 28, electric valve 29, capacitor 30, transformer 31, solar silicon panel 32, humidity sensor 33, insulating anti-corrosion outer layer 34, power cord 35, polymer humidity sensing film 36, insulating plate 37, comb-shaped electrode 38, bottom electrode 39, connecting terminal 40, collection component 60, control component 70, roadbed soil humidity automatic control system 50. DETAILED DESCRIPTION

[0040] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0041] The following describes the roadbed soil moisture automatic control system, design scheme generation method and medium of the embodiment of the present application with reference to the accompanying drawings. In response to the problem mentioned in the above background technology that current roadbed projects, especially low embankments or shallow cuttings with high groundwater levels, still lack a solution that can avoid clogging during the long-term service of the roadbed to maintain its good permeability and groundwater blocking performance, the present application provides a roadbed soil moisture automatic control system. In this system, a new type of geocomposite layer can be automatically controlled to actively absorb and drain the roadbed soil according to the humidity of both the roadbed soil and the external environment, so that the roadbed soil humidity is maintained at a constant and safe state for a long time.

[0042] Specifically, Figure 1 A schematic diagram of an automatic control system for roadbed soil moisture provided in an embodiment of the present application.

[0043] like Figure 1 As shown, the roadbed soil moisture automatic control system 50 includes: a geocomposite layer 7, a collection component 60 and a control component 70.

[0044] Among them, the geocomposite layer 7 includes first to third composite layers, the first composite layer absorbs moisture from the roadbed soil, the second composite layer discharges moisture from the roadbed soil, and the third composite layer blocks underground capillary water; the collection component 60 is used to collect the humidity of the roadbed soil and the external environment; the control component 70 performs humidity control operations on the geocomposite layer according to the humidity of the base soil and the external environment to control the geocomposite layer to absorb or discharge moisture from the roadbed soil.

[0045] It can be understood that the embodiment of the present application constructs an automatic control system 50 for roadbed soil moisture, including a geocomposite layer 7, a collection component 60 and a control component 70. The control component 70 can automatically control the geocomposite layer 7 to absorb or remove moisture from the roadbed soil based on the roadbed soil moisture and external ambient temperature collected by the collection component 60, so as to ensure that the roadbed is in a stable and safe working state for a long time during its service.

[0046] The collection component 60 can be a humidity sensor, and the humidity sensor can be a resistive sensor. The structure of the resistive sensor is as follows: Figure 2 As shown, it includes an insulating anti-corrosion outer layer 34, a power line 35, a polymer moisture-sensitive membrane 36, an insulating plate 37 (aluminum oxide substrate), a comb-shaped electrode 38, a bottom electrode 39, and a connecting terminal 40 (probe); the geocomposite layer 7 can also be called a geocomposite absorption-drainage-water blocking layer.

[0047] In the embodiment of the present application, the first composite layer is a gradient porosity wicking fiber geotextile layer, the second composite layer is a three-dimensional composite geonet layer, and the third composite layer is a geotextile layer.

[0048] Specifically, the structure of the gradient porosity wicking fiber geotextile layer is as follows Figure 3 As shown, Figure 3 It includes a road base 3, a three-dimensional composite geonet 10, a non-woven geotextile 11, a small-pore wicking fiber layer 12, a medium-pore wicking fiber layer 13, and a large-pore wicking fiber layer 14; the wicking fiber has a special cross-sectional structure such as Figure 4 As shown, Figure 4 The cross section of the geonet layer is shown in FIG1 , which includes a cross section of a blade 16, a cross section of a blade root 17, and a cross section of a blade tip 18. Figure 5 As shown, Figure 5 The structure includes main reinforcement bars 19, secondary reinforcement bars 20 and a resistance-drainage grid 21.

[0049] In the embodiment of the present application, the geocomposite layer 7 is laid horizontally along the roadbed as a whole, with the ends on both sides directly exposed to the external environment or attached to the inner walls of the drainage ditches on both sides of the road shoulders. The pore equivalent aperture of the first composite layer is linearly proportional to the contact distance of the upper surface of the second composite layer. The pore equivalent aperture of the first composite layer close to both sides of the road shoulders is larger than the preset aperture. The second composite layer includes longitudinally arranged ribs in the middle and cross-arranged ribs in the upper and lower parts. The rigidity of the longitudinally arranged ribs in the middle is greater than the rigidity of the cross-arranged ribs in the upper and lower parts. The upper and lower surfaces of the second composite layer are covered with a third composite layer.

[0050] Among them, the preset aperture can be set according to specific circumstances, and there is no specific limitation for comparison.

[0051] Specifically, the geocomposite layer 7 of the embodiment of the present application is laid along the roadbed as a whole, and the transverse cross section is as follows: Figure 6 As shown, Figure 6 It includes: surface layer 1, base layer 2, road base layer 3, ground base layer 4, groundwater 5, open drainage ditch 6, geocomposite layer 7, control unit 8, wherein the control unit 8 includes Figure 1 An acquisition component 60 and a control component 70 are shown.

[0052] The laying method of geocomposite layer is as follows Figure 7 As shown, Figure 7 It includes a road base layer 3, a ground base layer 4, a gradient pore wicking fiber geotextile 9, a three-dimensional composite geonet 10, a non-woven geotextile 11, and a wind hole 23. The ends on both sides are directly exposed to the external environment or attached to the inner walls of the drainage ditches on both sides of the road shoulders. The wicking fiber layer of the first composite layer directly in contact with the upper surface of the second composite layer has a larger equivalent pore size. The farther away from the upper surface of the geonet, the smaller the equivalent pore size of the wicking fiber layer. The pore sizes of adjacent wicking fiber layers are in a certain proportion. The large-pore wicking fiber layers are used at the two ends of the road, i.e., near the shoulders, i.e., the transverse ends of the wicking fiber fabric; the second composite layer is a geodetic drainage material with a three-layer special structure formed by longitudinally arranged ribs with greater rigidity in the middle and cross-arranged ribs with less rigidity; the third composite layer uses non-woven geotextile and is laid on the lower surface of the three-dimensional composite geonet.

[0053] In the embodiment of the present application, the control component 60 includes a ventilation device, a power output device, and a controller, wherein the controller controls the ventilation device and the power output device to perform humidity control operations.

[0054] In the embodiments of this application, Figure 8As shown, the ventilation device includes a ventilation pipe 22, a vertical riser 24 and a guide spiral wind hood 25, wherein the ventilation pipe 22 is symmetrically laid on the roadbed soil near the road shoulder, the pipe body of the ventilation pipe 22 is arranged in the first composite layer and the second composite layer, the pipe wall of the ventilation pipe 22 is provided with spirally distributed wind holes 23, the vertical riser 24 is connected to the horizontal ventilation pipe and is arranged perpendicular to the horizontal ventilation pipe 22, and the guide spiral wind hood 25, composed of guide blades and a top cap, is installed on the top of the vertical riser 22.

[0055] Specifically, the ventilation device of the embodiment of the present application mainly includes: a ventilation pipe 22, which is symmetrically laid on the roadbed soil near the shoulder of the road. The pipe body is wrapped by the above-mentioned gradient pore wicking fiber geotextile 9 and the three-dimensional composite geonet 10. The pipe wall is provided with wind holes 23, which are spirally distributed to enhance air convection; the vertical riser 24 is directly connected to the horizontal ventilation pipe 22 and is arranged perpendicular to the horizontal ventilation pipe; the guide spiral wind cap 25 is composed of spiral guide blades 26 and a top cap, and is installed on the top of the vertical riser 24.

[0056] In addition, it should be noted that the main design parameters of the guide spiral hood 25 include the hood diameter, the angle between the guide blades and the horizontal plane, and the blade height.

[0057] In an embodiment of the present application, the power output device includes an energy supply device 80 , a pump case 27 and an electric valve 29 , wherein the energy supply device supplies energy to the pump case 27 , and the electric valve 29 controls the ventilation speed of the pump case 27 .

[0058] The energy supply device 80 may be: Figure 8 The solar silicon panel 32 is shown in FIG.

[0059] Specifically, the power output device of the embodiment of the present application includes an energy supply device 80, a pump box 27 and an electric valve 29. The energy supply device 80 supplies energy to the pump box 27, and the electric valve 29 controls the ventilation speed of the pump box 27. Figure 8 As shown,

[0060] Pump housing 27 primarily includes a transformer 31, a capacitor 30 (battery), and an air pump 28. Air pump 28, powered by transformer 31, can output a duct velocity of 4 to 15 m / s. When operating, air pump 28 mechanically ventilates ventilation duct 22, increasing the wicking and evaporation rate of the geocomposite layer.

[0061] Specifically, the structure of the control unit in the embodiment of the present application is as follows: Figure 8 As shown, it mainly includes: a ventilation device, a power output device and a collection component 50. The collection component 50 in the embodiment of the present application is Figure 8 The humidity sensor 33 is shown as an example.

[0062] Among them, the ventilation device mainly includes: ventilation pipes 22, which are symmetrically laid on the roadbed soil near the shoulder of the road. The pipe body is wrapped by the above-mentioned gradient pore wicking fiber geotextile and three-dimensional composite geonet. The pipe wall is provided with air holes 23, which are spirally distributed to enhance air convection; the vertical riser 24 is directly connected to the horizontal ventilation pipe and is arranged perpendicular to the horizontal ventilation pipe 22; the guide spiral wind cap 25 consists of spiral guide blades 26 and a top cap, and is installed on the top of the vertical riser 24.

[0063] The main features of the power output device include: solar silicon panels 32, pump box 27 and electric valve 29.

[0064] The pump housing primarily includes a transformer 31, a capacitor 30 (battery), and an air pump 28. The air pump 28, powered by the transformer 31, can output a duct air velocity of 4 to 15 m / s. When the air pump is operating, it mechanically ventilates the ventilation duct 22, increasing the wicking and evaporation rate of the geocomposite layer.

[0065] The humidity sensor 33 used is a resistive sensor, wherein the internal structure of the resistive sensor is as follows Figure 2 As shown;

[0066] The humidity sensors 33 are installed in the roadbed soil at the center of the road and the road shoulder, as well as on the back of the solar silicon panel 32 on the vertical riser 25. By simultaneously detecting the humidity of the roadbed body, the lateral end of the geocomposite layer 7 (near the road shoulder), and the external environment, and integrating and comparing them, the appropriate roadbed dehumidification mode is selected based on the set safe humidity state of the roadbed soil. It mainly includes: natural ventilation mode and power ventilation mode.

[0067] The natural ventilation mode is to realize unpowered ventilation by utilizing the hot and cold convection of the outside air through the ventilation duct device; the powered ventilation mode is to realize mechanical ventilation through the above-mentioned air pump to provide a greater duct wind speed for the ventilation duct.

[0068] According to the automatic control system for roadbed soil moisture proposed in the embodiment of the present application, it includes a geocomposite layer, a collection component and a control component. The control component can automatically control the geocomposite layer to absorb or remove moisture from the roadbed soil based on the roadbed soil moisture and external ambient temperature collected by the collection component, so as to ensure that the roadbed is in a stable and safe working state for a long time during its service.

[0069] Next, a method for generating a design scheme for a geocomposite layer according to an embodiment of the present application will be described with reference to the accompanying drawings.

[0070] Figure 9 It is a flow chart of a method for generating a design solution for a geocomposite layer according to an embodiment of the present application.

[0071] like Figure 9 As shown, the method for generating a design scheme of a geocomposite layer is used to generate a design scheme of a geocomposite layer in the above-mentioned roadbed soil moisture automatic control system, and includes the following steps:

[0072] In step S101 , the environmental conditions of the subgrade soil are obtained, wherein the environmental conditions include whether the subgrade soil is in a saturated or unsaturated state, whether the subgrade soil is in an oversaturated state, and whether the subgrade soil has a capillary phenomenon.

[0073] In step S102, the absorption-diffusion-evaporation coupling efficiency of the first composite layer is calculated according to whether the subgrade soil is in a saturated or unsaturated state, the drainage rate of the second composite layer is calculated according to whether the subgrade soil is in an oversaturated state, and the blocking efficiency of the third composite layer is calculated according to the capillary phenomenon of the subgrade soil.

[0074] Since the roadbed soil is in a saturated or unsaturated state, the moisture state of the roadbed soil is further reduced or improved mainly through the wicking-diffusion-evaporation coupling effect of the above-mentioned wicking fiber geotextile layer (i.e., the first composite layer); when the roadbed soil is in an oversaturated state due to climatic conditions such as rainfall, drainage is mainly carried out by the above-mentioned second composite layer; the underground capillary water of the roadbed soil is mainly blocked by the third composite layer, because it has larger pores and its own thickness, the embodiment of the present application can determine the parameters of different geocomposite layers based on the specific state of the roadbed soil.

[0075] In step S103, the parameter range of the corresponding composite layer is determined according to the absorption-diffusion-evaporation coupling efficiency, the drainage rate and the blocking efficiency, and a design scheme of the geocomposite layer is generated according to the road engineering requirements and the parameter range.

[0076] It is understandable that the embodiment of the present application can determine the parameter range of the corresponding composite layer according to the absorption-diffusion-evaporation coupling efficiency, drainage rate and blocking efficiency, and generate a design scheme of the geocomposite layer according to the road engineering requirements and parameter range, which can meet different actual working conditions and engineering requirements on site and improve the safety and accuracy of road subgrade engineering.

[0077] In the embodiment of the present application, the calculation formula of the absorption-diffusion-evaporation coupling efficiency is:

[0078]

[0079] Among them, (ET) f is the absorption-diffusion-evaporation coupling rate, is the actual net radiation, G is the soil heat flux, ρ air is the air density, c p is the specific heat of air at constant pressure, e s is the temperature Tair The saturated water vapor pressure of the air, e s is the temperature T air The actual water vapor pressure of the air at that time, is the equivalent aerodynamic impedance, λ is the latent heat of water vaporization, Δ is the slope of the saturated water vapor pressure curve, γ is the dry and wet constant, is the equivalent surface impedance, K ec is the absorption-diffusion-evaporation coupling coefficient;

[0080] The calculation formula for drainage rate is:

[0081]

[0082] in, is the drainage rate of the second composite layer, θ K is the hydraulic conductivity of the three-dimensional composite geonet, δ is the total thickness of the three-dimensional composite geonet, W is the longitudinal width of the geonet, δ1 and δ2 are the thickness of the main reinforcement and the secondary reinforcement respectively, s is the spacing of the equal-diameter reinforcements, is the included angle of the top projection of the primary and secondary reinforcement, θ net is the contact angle between the rib material and the transmission liquid infiltration interface, K P is the external load correction factor, K η is the material wettability correction factor;

[0083] The calculation formula for blocking efficiency is:

[0084]

[0085] Among them, η f is the blocking efficiency of the second composite layer, h 0-gd is the theoretical rising height of underground capillary water, h gd is the actual rising height of underground capillary water, θ net is the contact angle between the reinforcement material and the underground capillary water infiltration interface, f1 is the retardation correction constant, and δ is the actual thickness of the geonet.

[0086] Specifically, the specific calculation method of the absorption-diffusion-evaporation coupling efficiency, drainage rate and blocking efficiency in the embodiment of the present application is as follows.

[0087] 1. For saturated or unsaturated subgrade soil, the moisture state of the subgrade soil is further reduced or improved mainly through the wicking-diffusion-evaporation coupling effect of the above-mentioned wicking fiber geotextile layer (first composite layer). The wicking-diffusion-evaporation coupling efficiency (i.e., the wicking-evaporation coupling efficiency of the wicking fiber fabric layer) is calculated as follows:

[0088] 1. According to fluid mechanics and Laplace equation, the interfacial pressure in the capillary can be expressed as:

[0089]

[0090] Wherein, σ is the surface tension coefficient of the liquid (taken as 0.0725), P is the interfacial pressure in the capillary, r is the capillary radius, and θ is the contact angle of the two-phase (solid-liquid or gas-liquid) interface.

[0091] Wicking fiber geotextiles use tiny capillary channels formed between fibers to transfer liquid to achieve wicking of the fabric. Combined with formula (1), the conditions for the differential wicking capillary effect between the fabric and the roadbed soil to produce wicking are obtained:

[0092]

[0093] ΔP0=P f0 -P s >0; (2)

[0094] Among them, P s is the capillary suction of the subgrade soil, θ s The contact angle between the soil and the liquid infiltration interface (generally 30-60°), σ liquid surface tension coefficient (taken as 0.0725), d L10 Effective particle size of roadbed soil particles, P f0 is the theoretical capillary pressure of a single wicking fiber pore, θ f is the contact angle between the wicking fiber and the liquid infiltration interface (usually 0°~40°), r po is the theoretical capillary radius of a single wicking fiber pore, and ΔP0 is the theoretical capillary pressure difference between the wicking fiber pore and the soil pore.

[0095] The wicking effect of the fiber refers to the capillary effect process of the fiber pores. According to the capillary effect equation, the theoretical capillary rise height h of a single wicking fiber pore is obtained. f0 :

[0096]

[0097] Among them, h f0 is the theoretical capillary rise height of a single wicking fiber pore, ρ is the density of water (1000kg / m 3 ), r po is the theoretical capillary radius of a single wicking fiber pore, σ is the liquid surface tension coefficient (taken as 0.0725), θ f It is the contact angle between the wicking fiber and the liquid infiltration interface (generally 0°~40°).

[0098] Combining formula (2) and the Poiseuille equation, the theoretical wicking rate q in the capillary pores of a single wicking fiber is obtained: f0 :

[0099]

[0100] Among them, q f0 is the theoretical wicking rate of a single wicking fiber pore, Q f0 is the theoretical flow rate of the wicking fiber, ΔP is the actual capillary pressure difference at the contact between the wicking fiber pores and the soil pores, η is the liquid viscosity (water is 0.001), h f0 It is the theoretical capillary rise height of a single wicking fiber pore.

[0101] 2. The shape parameters of the wicking fiber itself include the fiber shape factor χ, specific surface area S ssa , and the resulting geotextile weaving parameters include fiber density ρ f , porosity ε and tortuosity τ:

[0102]

[0103]

[0104] Where ε is the porosity of the wicking fiber fabric, ρ sur is the apparent density of wicking fiber fabric, ρ f is the actual density of the wicking fiber fabric; τ is the internal tortuosity of the wicking fiber fabric, L t is the actual path length of the fiber, L0 is the intuitive length of the fiber; m f is the quality of wicking fiber fabric, V f is the volume of the wicking fiber fabric; χ is the wicking fiber shape factor, L is the distance from the root to the tip of the longitudinal section of a single wicking fiber bundle, R is the tip radius of the longitudinal section of a single wicking fiber bundle, a is the angle between adjacent lobes in the longitudinal section of a single wicking fiber bundle, a0, a1, and a2 are all shape factor fitting constants; S ssa is the specific surface area of ​​the wicking fiber fabric, d f is the diameter of a single bundle of wicking fibers (if the cross section is irregular, it is the diameter of the circumscribed circle of the cross section), χ is the shape factor of the wicking fiber, b χ is the shape factor correction constant.

[0105] According to the definition of hydraulic radius and combined with equations (5) to (9), the actual equivalent capillary radius r of the pores of the wicking fiber is obtained. p The expression:

[0106]

[0107] Among them, r p is the actual equivalent capillary radius of the wicking fiber pore, ε is the porosity of the wicking fiber fabric, S ssa is the specific surface area of ​​the wicking fiber fabric, d f is the diameter of a single bundle of wicking fibers (if the cross section is irregular, it is the diameter of the circumscribed circle of the cross section), a χis the shape factor correction constant, χ is the wicking fiber shape factor, and τ is the internal tortuosity of the wicking fiber fabric.

[0108] The theoretical capillary rise height h of a single wicking fiber pore in equations (2) to (4) is f0 and theoretical wicking rate q f0 Correction is performed to obtain the actual capillary pressure P of a single wicking fiber pore f , the actual capillary pressure difference ΔP at the contact between a single wicking fiber pore and the soil pore, and the capillary rise height h f and the actual wicking rate q f1 :

[0109]

[0110] Among them, P f is the actual capillary pressure of a single wicking fiber pore, σ is the liquid surface tension coefficient (taken as 0.0725), ε is the porosity of the wicking fiber fabric, θ f is the contact angle between the wicking fiber and the liquid infiltration interface (usually 0°~40°), a X is the shape factor correction constant, τ is the internal tortuosity of the wicking fiber fabric, d f is the diameter of a single bundle of wicking fibers (if the cross section is irregular, it is the diameter of the circumscribed circle of the cross section), ΔP is the actual capillary pressure difference at the contact between the pores of the wicking fibers and the pores of the soil, P f Actual capillary pressure of a single wicking fiber pore, P s is the capillary suction of the subgrade soil, h f is the actual capillary rise height of a single wicking fiber pore, ρ is the density of water (1000kg / m 3 ), b X is the shape factor correction constant, χ is the wicking fiber shape factor, and η is the liquid viscosity (0.001 for water).

[0111] 3. The moisture state of the roadbed soil is the saturation S r The soil saturation correction coefficient Γ is introduced to affect the wicking rate of wicking fiber geotextiles. It is considered that the soil saturation is in a high saturation state when [0.7-1], and Γ can be approximately equal to 1:

[0112]

[0113] Where Γ is the saturation correction coefficient of the roadbed soil, S r Subgrade soil saturation, K sf Soil-fiber moisture transfer coefficient, K Γ is the saturation correction coefficient fitting constant.

[0114] 4. According to the Kozeny-Carman equation, the permeability of porous media is:

[0115]

[0116] Where K is the permeability, ε is the porosity of the wicking fiber fabric, C is the Kozeny-Carman constant, S ssa is the specific surface area of ​​the wicking fiber fabric.

[0117] Considering the influence of the shape parameters of the wicking fiber and the wettability of the fiber material on the equivalent permeability of its gradient pore wicking fiber, the equivalent permeability K of the wicking fiber is obtained by combining equations (9) and (16): f :

[0118]

[0119] Among them, K f is the equivalent permeability of the wicking fiber, ε is the porosity of the wicking fiber fabric, σ is the surface tension coefficient of the liquid (taken as 0.0725), θ f is the contact angle between the wicking fiber and the liquid infiltration interface (generally 0°~40°), C is the Kozeny-Carman constant, τ is the internal tortuosity of the wicking fiber fabric, d f is the diameter of a single bundle of wicking fibers (if the cross section is irregular, it is the diameter of the circumscribed circle of the cross section), and η is the viscosity of the liquid (0.001 for water).

[0120] The gradient porosity wicking fiber geotextile also needs to consider the effect of its gradient porosity setting on its fabric permeability. It is believed that the wicking fiber located in the main part of the roadbed mainly has a wetting and wicking effect perpendicular to the road surface. Combined with formula (16), the equivalent horizontal permeability K is calculated using the layered summation method. Hf and equivalent vertical permeability K Vf :

[0121]

[0122] Among them, K Hf is the equivalent horizontal permeability of the gradient pore wicking fiber, K fHi is the equivalent horizontal permeability of each layer of gradient pore wicking fiber, h fHi is the horizontal thickness of each layer of gradient pore wicking fiber, K Vf is the equivalent vertical permeability of the gradient pore wicking fiber, h fVi K is the thickness of each layer of gradient pore wicking fiber vertically. fvi is the equivalent vertical permeability of each layer of gradient pore wicking fiber.

[0123] 5. Considering the influence of external load factors such as road traffic on the above-mentioned wicking fiber geotextile, the fiber fabric load correction factor K is introduced fP :

[0124]

[0125] Among them, K fP is the load correction factor for fiber fabrics, P F is the external load on the fabric, a P 、b P Both are fiber fabric load correction constants.

[0126] 6. When the porosity of the wicking fiber fabric is ε, the number of pores per unit cross-sectional area is N ε for:

[0127]

[0128] Among them, N ε is the number of pores per unit cross-sectional area, r p is the actual equivalent capillary radius of the pores of the wicking fiber, and ε is the porosity of the wicking fiber fabric.

[0129] Combining the four equations (12), (14), (19) to (21), we can get the actual wicking velocity q of the gradient pore wicking fiber geotextile: f :

[0130]

[0131] in, is the actual wicking flow rate, ρ is the density of water (1000 kg / m 3 ), d f is the diameter of a single bundle of wicking fibers (if the cross section is irregular, it is the diameter of the circumscribed circle of the cross section), ε is the porosity of the wicking fiber fabric, τ is the internal tortuosity of the wicking fiber fabric, χ is the wicking fiber shape factor, η is the liquid viscosity (water is 0.001), ΔP is the actual capillary pressure difference at the contact between the wicking fiber pores and the soil pores, and θ f is the contact angle between the wicking fiber and the liquid infiltration interface (usually 0°~40°), σ is the surface tension coefficient of the liquid (taken as 0.0725), K sf is the soil-fiber moisture transfer coefficient, S r is the saturation of roadbed soil, K Γ is the saturation correction coefficient fitting constant, P F is the external load on the fabric, a P 、b P are the fiber fabric load correction constants, h fVi K is the thickness of each layer of gradient pore wicking fiber vertically. fVi is the equivalent vertical permeability of each layer of gradient pore wicking fiber.

[0132] 7. According to the general form of the Penman-Monteith equation, the possible evaporation rate of wicking fiber fabric can be obtained:

[0133]

[0134] Where, (ET)0 is the theoretical possible evaporation rate of the wicking fiber fabric, R n is the theoretical net radiation, G is the soil heat flux, ρ air is the air density, C p is the specific heat of air at constant pressure, e s is the temperature T air The saturated water vapor pressure of the air, e a is the temperature T air The actual water vapor pressure of the air at that time, r a is the aerodynamic impedance, λ is the latent heat of water vaporization, Δ is the slope of the saturated water vapor pressure curve, γ is the dry-wet constant, r c is the surface impedance.

[0135] Considering the wicking fiber's own conditions and external environmental conditions, the aerodynamic impedance r in formula (23) is a , surface (canopy) impedance r c and theoretical net radiation R n Make corrections:

[0136]

[0137] in, is the equivalent surface impedance, η is the liquid viscosity (water is 0.001), σ is the liquid surface tension coefficient (taken as 0.0725), θ f is the contact angle between the wicking fiber and the liquid infiltration interface (usually 0°~40°), d f is the diameter of a single bundle of wicking fibers (if the cross section is irregular, it is the diameter of the circumscribed circle of the cross section), ρ air is the air density, τ is the internal tortuosity of the wicking fiber fabric, χ is the wicking fiber shape factor, is the equivalent aerodynamic impedance, Z is the height of the wicking fiber fabric layer exposed to the air above 2m (usually 2m), h fVi R is the thickness of each layer of gradient pore wicking fiber vertically. n is the theoretical net radiation, is the actual net radiation, α f is the reflectivity of the wicking fiber (usually 0.1-0.25), ∈ f is the wicking fiber emissivity (usually 0.8-0.95), σ sb is the Stefan-Boltzmann constant (taken as 5.67×10 -8 W / m 2·K 4 ), T air is the outside air temperature, U Z is the wind speed in the ventilation duct, and k is the Karman constant (taken as 0.41).

[0138] Different ventilation modes require the wind speed U in the ventilation duct in formula (25) to be adjusted. Z Make corrections, in natural ventilation mode (Z=H):

[0139]

[0140] in, is the wind speed in the ventilation duct under natural ventilation mode, ρ air is the air density, ΔP w is the dynamic pressure difference generated by the rotation of the hood, ΔP t is the pressure difference caused by the thermal pressure effect in the vertical riser, α f is the reflectivity of the wicking fiber, K U is the corrected wind speed coefficient, U w Wind speed at the spiral guide hood, θ d is the angle between the guide vane and the horizontal plane, D d is the hood diameter, ΔT is the temperature difference between the ventilation duct and the outside environment, H is the vertical riser height, T air The outside temperature.

[0141] In power ventilation mode:

[0142]

[0143] Among them, U z is the wind speed in the ventilation duct, is the wind speed in the ventilation duct under power ventilation mode, U 泵 It is the actual output wind speed of the air pump.

[0144] 8. Introducing the humidity influence coefficient of wicking fiber ξ f and the fiber wicking-evaporation coupling coefficient K ec :

[0145]

[0146] Among them, ξ f is the humidity influence coefficient of wicking fiber, W f is the current moisture regain of the wicking fiber, W f-sat is the saturated moisture regain of the wicking fiber, k ξ 、n W All are fitting constants of the humidity influence coefficient of wicking fibers. is the actual wind speed in the ventilation duct under different modes, RH is the relative humidity of the environment, τ is the internal tortuosity of the wicking fiber fabric, ε is the porosity of the wicking fiber fabric, and χ is the shape factor of the wicking fiber.

[0147] Combining equations (23)-(30), we can obtain the actual wicking-evaporation coupling rate (ET) of the wicking fiber fabric: f :

[0148]

[0149] Among them, (ET) f is the wicking-evaporation coupling rate of the wicking fiber, is the actual net radiation, G is the soil heat flux, ρ air is the air density, C p is the specific heat of air at constant pressure, e s is the temperature T air The saturated water vapor pressure of the air, e s is the temperature T air The actual water vapor pressure of the air at that time, is the equivalent aerodynamic impedance, λ is the latent heat of water vaporization, Δ is the slope of the saturated water vapor pressure curve, γ is the dry and wet constant, is the equivalent surface impedance, K ec is the fiber wicking-evaporation coupling coefficient.

[0150] 9. It is believed that the diffusion-evaporation effect mainly occurs in the wicking fiber layer located on both sides of the roadbed soil near the shoulder. When the evaporation rate (ET) f Less than its wicking rate and equivalent horizontal permeability K Hf When the product of , satisfies the dynamic balance equation of wicking-evaporation energy:

[0151]

[0152] in, is the wicking rate, K Hf is the equivalent horizontal permeability of the gradient pore wicking fiber, (ET) f is the wicking-evaporation coupling rate of the wicking fiber, S f It is the amount of moisture stored on the surface of the wicking fiber.

[0153] 2. When the roadbed soil is in an oversaturated state due to climatic conditions such as rainfall, the drainage is mainly carried out by relying on the above-mentioned three-dimensional composite geonet (second composite layer). The drainage rate is calculated as follows:

[0154] It is known that according to Darcy's law:

[0155]

[0156] Among them, Q is the seepage rate per unit time, A is the water flow section, is the hydraulic gradient, Δh is the total head loss, L is the seepage path length, and K is the permeability coefficient. According to the relevant parameters and characteristics of the three-dimensional composite geonet and considering the actual working conditions, the relevant parameters in formula (33) are modified.

[0157] 1. The three-dimensional composite geonet is mainly composed of longitudinally arranged main ribs and cross-arranged secondary ribs on the upper and lower sides. Therefore, the water-passing section is determined by the rib size and arrangement of the geonet. In order to simplify the calculation, the rib shape is regarded as cylindrical, and the equivalent water-passing section of the three-dimensional composite geonet is and actual porosity They are:

[0158]

[0159]

[0160] in, is the water-passing section, W is the longitudinal width of the geonet, δ1 and δ2 are the thickness of the main reinforcement and the secondary reinforcement (i.e., the diameter of the reinforcement cross section), is the included angle of the primary and secondary reinforcement projections (0° to 90°), s is the spacing of equal-diameter reinforcement bars (5 to 20δ, δ is the total thickness of the three-dimensional composite geonet), is the actual porosity of the three-dimensional composite geonet.

[0161] Combining equations (34) and (35), we can derive the equivalent water surface calculation formula for the three-dimensional composite geonet:

[0162]

[0163] 2. Use hydraulic conductivity θ K To describe the permeability of three-dimensional composite geonet:

[0164] θ K =Kδ; (37)

[0165] Among them, θ K is the hydraulic conductivity of the three-dimensional composite geonet, K is the permeability of the three-dimensional composite geonet, and δ is the total thickness of the three-dimensional composite geonet.

[0166] 3. Due to external factors such as road traffic loads, the compression effect on the above-mentioned geonet will reduce the initial thickness of the geonet and thus affect its drainage performance. The external load correction factor K is introduced. P :

[0167]

[0168] Among them, K P is the external load correction factor, KP1 , K P2 (0 <K P1 , K P1 <1) is the load correction term constant, P max is the maximum load that the three-dimensional geonet can withstand, and P is the external load on the three-dimensional geonet.

[0169] 4. The wetting characteristics between the geonet core material properties and the drainage liquid will also affect its own drainage rate, so the material wettability correction coefficient K is introduced. η :

[0170]

[0171] Among them, K η is the material wettability correction coefficient, θ net is the contact angle between the rib material and the transmission liquid infiltration interface (generally 95-120°), K η1 (0.1~0.5) is the wettability correction constant.

[0172] 5. The head loss of the flow through the three-dimensional composite geonet is related to the wettability of the reinforcement material and the transmitted liquid. The head loss expression of the liquid flowing through the three-dimensional composite geonet is obtained

[0173]

[0174] in, is the water head consumed by the three-dimensional geonet, is the total thickness of the three-dimensional composite geonet, θ net It is the contact angle between the rib material and the transmission liquid infiltration interface (generally 95-120°).

[0175] Combining equations (33) and (36)-(41), and assuming that the length of the seepage path through the three-dimensional geonet is the total thickness of the geonet, the drainage rate expression of the three-dimensional composite geonet is obtained:

[0176]

[0177] in, is the drainage rate of the three-dimensional composite geonet, θ K is the hydraulic conductivity of the three-dimensional composite geonet, δ is the total thickness of the three-dimensional composite geonet, W is the longitudinal width of the geonet, δ1 and δ2 are the thickness of the main reinforcement and the secondary reinforcement respectively (i.e., the diameter of the reinforcement cross section), s is the spacing between the equal-diameter reinforcements (5-20δ), The included angle of the primary and secondary reinforcement projections (0° to 90°), θ net is the contact angle between the rib material and the transmission liquid infiltration interface (generally 95-120°), K P is the external load correction factor, Kη is the material wettability correction factor.

[0178] 3. The above-mentioned geocomposite absorption-drainage-blocking layer blocks the capillary water action of underground water by relying on the three-dimensional composite geonet due to its larger pores and its own thickness. A method for calculating the blocking efficiency of the above-mentioned three-dimensional composite geonet (second composite layer) on the capillary water action of underground water below the roadbed is provided, including a method for calculating the key size parameters of the required geonet according to actual working conditions.

[0179] 1. According to the capillary phenomenon formula, the theoretical rise height of groundwater capillary action below the roadbed can be obtained:

[0180]

[0181] Among them, h 0-gd is the theoretical rising height of underground capillary water, σ u is the groundwater surface tension coefficient, θ soil is the contact angle of the infiltration interface between groundwater and soil particles under the roadbed, ρ u is the density of groundwater, g is the acceleration due to gravity, d 10 is the effective particle size of the soil under the roadbed.

[0182] 2. The retardation effect of the geonet mainly depends on the grid size formed and the wetting effect of the core material on the capillary rising liquid. The retardation correction coefficient f is introduced.

[0183]

[0184] Among them, f is the retardation correction coefficient (0.85~1), f1 is the retardation correction term constant (0.1~0.3 for sand and 0.3~0.5 for clay), θ net is the contact angle between the reinforcement material and the underground capillary water infiltration interface, and δ is the actual thickness of the geonet.

[0185] Combining equations (42) and (43), we can get the actual height h of groundwater capillary action below the roadbed after laying the above geonet. gd :

[0186] h gd =fh 0-gd ; (44)

[0187] Among them, h gd is the actual rising height of underground capillary water, f is the retardation correction coefficient (0.85~1), h 0-gd is the theoretical rising height of underground capillary water.

[0188] According to equations (42) to (44), the retardation efficiency of the three-dimensional geonet can be obtained as follows:

[0189]

[0190] Among them, η f is the blocking efficiency of the three-dimensional geonet, h 0-gd is the theoretical rising height of underground capillary water, h gd is the actual rising height of underground capillary water, θ net is the contact angle of the reinforcement material and the underground capillary water infiltration interface, f1 is the retardation correction constant (0.1-0.3 for sand and 0.3-0.5 for clay), and δ is the actual thickness of the geonet.

[0191] 3. In actual working conditions, it is generally believed that the blocking efficiency is greater than or equal to f, which means that the blocking requirements of the road project are met. Combining formula (45), the minimum thickness of the geonet that meets the blocking requirements can be obtained as δ min :

[0192]

[0193] Among them, δ min is the theoretical minimum thickness of the geonet, f is the retardation correction coefficient (0.85~1), θ met is the contact angle of the reinforcement material and the underground capillary water infiltration interface, and f1 is the retardation correction constant (0.1-0.3 for sand and 0.3-0.5 for clay).

[0194] 4. Considering the external loads such as road traffic and the dynamic change intensity of groundwater level, the actual thickness of the geonet needs to be increased, and the three-dimensional geonet thickness correction factor K is introduced. δ , so the actual geonet thickness δ used in the project is:

[0195]

[0196] Among them, δ is the actual thickness of the geonet, θ net The contact angle between the reinforcement material and the underground capillary water infiltration interface, f is the retardation correction coefficient (0.85~1), f1 is the retardation correction constant (0.1~0.3 for sand and 0.3~0.5 for clay), K δ It is the correction factor of the thickness of the three-dimensional geonet (1.1-2.0).

[0197] In summary, the design scheme generation method of the geocomposite layer in the embodiment of the present application provides a calculation method for the working efficiency of the geocomposite layer, fully considers the relevant parameters such as the structural dimensions and material properties of each layer of the geocomposite layer, and combines the direct interaction relationship between soil, geotechnical materials and external environment. It better solves the problem that the traditional single isolated calculation and analysis method of the absorption and drainage performance of geotechnical materials is affected by the actual geological environment and the external environment, resulting in large errors from the actual situation; and includes a calculation method for the wicking-evaporation coupling efficiency of the wicking fiber fabric layer, the drainage rate of the three-dimensional compound geonet and the groundwater retardation efficiency calculation method, which provides a more reliable basis for the selection and design combination of relevant parameters of the geotechnical materials of each layer of the above-mentioned new geocomposite layer according to different actual on-site working conditions and engineering requirements, thereby improving the safety and accuracy of road subgrade projects.

[0198] It should be noted that the above explanation of the embodiment of the automatic control system for roadbed soil moisture is also applicable to the design scheme generation method of the geocomposite layer of this embodiment, and will not be repeated here.

[0199] According to the design scheme generation method of the geocomposite layer proposed in the embodiment of the present application, the absorption-diffusion-evaporation coupling efficiency, drainage rate, and blocking efficiency corresponding to each layer in the geocomposite layer under different environments can be calculated according to the environmental conditions of the roadbed soil, and then the parameter range of the corresponding composite layer can be determined according to the absorption-diffusion-evaporation coupling efficiency, drainage rate, and blocking efficiency. The design scheme of the geocomposite layer is generated according to the road engineering requirements and parameter range to improve the safety and accuracy of the road subgrade engineering.

[0200] The following describes the calculation process of the absorption-diffusion-evaporation coupling efficiency, drainage rate and blocking efficiency in the design scheme generation method of the geocomposite layer of the present application through a specific embodiment.

[0201] 1. Calculate the actual wicking flow rate of the wicking fiber under actual wicking action

[0202]

[0203] in, is the actual wicking velocity of the wicking fiber, θ f is the contact angle between the wicking fiber and the liquid infiltration interface, h f is the actual capillary rise height of the wicking fiber pores, r p is the actual equivalent capillary radius of the wicking fiber pore, η is the liquid viscosity (water is 0.001), ε is the porosity of the wicking fiber fabric, τ is the internal tortuosity of the wicking fiber fabric, χ is the wicking fiber shape factor, d f is the diameter of a standard circle with equal circumference of a single bundle of wicking fiber fabric, c χ are all shape factor correction constants, S rSubgrade soil saturation, K sf Soil-fiber moisture transfer coefficient, K Γ is the saturation correction coefficient fitting constant, K fVi is the equivalent vertical permeability of each layer of the gradient pore wicking fiber, K fHi is the equivalent horizontal permeability of each layer of gradient pore wicking fiber, h fVi h is the thickness of each layer of gradient pore wicking fiber vertically. fVi is the thickness of each layer of gradient pore wicking fiber horizontally, P F is the external load on the fabric, a P 、b P Both are fiber fabric load correction constants.

[0204] 2. Calculate the actual evaporation rate (ET) of wicking fiber fabrics f :

[0205]

[0206] Among them, (ET) f is the wicking-evaporation coupling rate of the wicking fiber, λ is the latent heat of water vaporization, Δ is the slope of the saturated water vapor pressure curve, is the actual net radiation, G is the soil heat flux, λ is the latent heat of water vaporization, ρ air is the air density, C p is the specific heat of air at constant pressure, t air is the actual temperature, e s is the temperature T air The saturated water vapor pressure of the air, e s is the temperature T air The actual water vapor pressure of the air at that time, γ is the dry and wet constant, is the equivalent surface impedance, is the equivalent aerodynamic impedance, k is the Karman constant (taken as 0.41), k ec is the fiber wicking-evaporation coupling coefficient.

[0207] 3. Determine the retardation efficiency η of the three-dimensional composite geonet on groundwater based on the on-site geological conditions, including the basic conditions of the groundwater level. f :

[0208]

[0209] According to the blocking efficiency η f Design requirements and determine the thickness δ requirements of the three-dimensional composite geonet:

[0210]

[0211] Among them, h 0-gd is the theoretical rising height of underground capillary water, hgd is the actual rising height of underground capillary water, g is the acceleration of gravity, δ is the actual thickness of the geonet, θ net The contact angle between the rib material and the underground capillary water infiltration interface, η f is the retardation efficiency of the three-dimensional geonet, f is the retardation correction coefficient (0.85~1), f1 is the retardation correction term constant (0.1~0.3 for sand and 0.3~0.5 for clay), K δ It is the correction factor of the thickness of the three-dimensional geonet (1.1-2.0).

[0212] 4. Combined with the actual thickness of the three-dimensional composite geonet determined in step 3, calculate the drainage rate of the three-dimensional composite geonet

[0213]

[0214] in, is the drainage rate of the three-dimensional composite geonet, θ K is the hydraulic conductivity of the three-dimensional composite geonet, is the water head loss flowing through the three-dimensional geonet, δ is the actual thickness of the three-dimensional composite geonet, W is the width of the geonet, δ1 and δ2 are the thickness of the main reinforcement and the secondary reinforcement respectively (i.e., the diameter of the reinforcement cross section circle), s is the spacing between the equal-diameter reinforcements, is the included angle between the secondary reinforcement and the main reinforcement (0°~90°), θ net is the contact angle between the rib material and the transmission liquid (95-115°), K P is the external load correction factor, K η is the material wettability correction factor, K P1 , K P1 (0 <K P1 , K P1 <1) is the load correction term constant, K η1 (0.1~0.5) is the wettability correction constant.

[0215] Take a roadbed project as an example. The latitude of the area is 30°N and the altitude is 50m. It is known that the roadbed soil is mainly sandy silt with an effective particle size of 10μm. The contact angle between soil particles and water is 45°. The external loads such as traffic loads P F The pressure is 50kPa, the roadbed slope is 1:1.5, the overall roadbed height is 2m, the upper roadbed width is 10m, and the lower embankment width is 16m. The three-dimensional composite geonet blocking efficiency is required to be no less than 95%.

[0216] The longitudinal width of the geonet is 1m, and the hydraulic conductivity is 1.5×10 -3 m 2 / s, the spacing between equal-diameter bars is 10 times the total thickness of the three-dimensional geonet, the wettability correction term constant is 0.30, and the maximum load that the three-dimensional geonet can withstand is 2000kPa.

[0217] The gradient porosity wicking fiber model is set to 2 layers, with layer A having a porosity of 50%, a thickness of 1 mm, and a fiber diameter of 20 μm; layer B having a porosity of 60%, a thickness of 1 mm, and a fiber diameter of 35 μm; layer C, i.e., the porosity of the wicking fiber fabric at both ends in the transverse direction is 75%, a thickness of 2 mm, and a fiber diameter of 45 μm; that is, the porosity gradient index is set to 0.38. The shape factor and tortuosity of the wicking fiber of the angle section are taken as 1.2 and 1.5 respectively; the shape factor and tortuosity of the wicking fiber of the cross section are taken as 1.5 and 1.8 respectively; the shape factor and tortuosity of the wicking fiber of the five-pointed star section are taken as 2.2 and 2.5 respectively; the shape factor and tortuosity of the wicking fiber of the circular section are taken as 1 and 1.4 respectively; the shape factor correction constant is 1; the soil-fiber moisture transfer coefficient is 2, the saturation correction coefficient fitting constant is 3, the fiber fabric load correction constant is 0.2, the wicking fiber reflectivity and emissivity are 0.1 and 0.9 respectively, the Kozeny-Carman constant is 5, the saturated moisture regain of the wicking fiber is 10%, the current moisture regain of the wicking fiber is 6%, and k ξ 、n W The fitting constants of the wicking fiber humidity influence coefficient are all 1, and the load correction term constant K P1 and K P2 They are taken as 0.6 and 0.8 respectively, the three-dimensional geonet thickness correction coefficient is taken as 1.4, the hysteresis correction term constant is taken as 0.3, and the soil saturation correction coefficient is taken as 1.

[0218] The surface tension coefficient and viscosity of groundwater and rainwater are taken as 0.072 and 10 respectively. -3 Pa / s, the contact angle between the wicking fiber and the water-wetting interface is 0°, the contact angle between the geonet reinforcement and the water-wetting interface is 110°, and the reinforcement material is HDPE with a density of 0.95g / cm 3 , can withstand a maximum external load of 1200kPa.

[0219] The external ambient temperature is 25°C, the relative humidity is 50%, the soil heat flux is 0 MJ / (m2·d), the dry-wet constant is 0.067 kPa / °C, and the air density is 1.29 kg / m 3 ; The specific heat of air at constant pressure is 1.012×10 -3 MJ / (kg·K), the slope of the saturated water vapor pressure curve is 1.65kPa / ℃, and the theoretical net radiation is 900MJ / (m 2 ·d).

[0220] The inner diameter of the ventilation duct is 10 cm, the height and diameter of the vertical riser are 6 m and 15 cm respectively, the diameter of the hood is 20 cm, the wind speed at the spiral guide hood is 5 m / s, the angle between the guide blade and the horizontal plane is 45°, and the temperature difference between the inside of the ventilation duct and the external environment is 1°C.

[0221] Based on the retardation efficiency requirements for a three-dimensional composite geonet, the calculated minimum thickness is 9.573 mm. Based on the required thickness, drainage rate calculations and experimental tests were performed for three different geonet sizes. Table 1 shows the results for these geonets.

[0222] Table 1

[0223]

[0224]

[0225] The wicking efficiency of wicking fibers with special-shaped cross-sections was calculated and experimentally tested under the same circumscribed circle diameter. The parameters and types of the special-shaped cross-sections of wicking fibers are shown in Table 2.

[0226] Table 2

[0227]

[0228] The evaporation rate calculation and experimental test were carried out for the wicking fiber with different shaped cross-sections under the same circumscribed circle diameter. This embodiment selected the natural ventilation mode for analysis. Table 3 shows the parameters of different wicking fiber shaped cross-sections.

[0229] Table 3

[0230]

[0231]

[0232] Combine Figure 10 The relationship curve diagram shown includes geonet specifications-drainage rate calculation value / experimental value as shown in Figure 10 (a) Cross-sectional shape of wicking fiber - equivalent capillary radius of pores Figure 10 (b), cross-sectional shape of wicking fiber-calculated value of wicking efficiency / experimental value Figure 10 (c) and the relationship curve between the cross-sectional shape of the wicking fiber and the calculated value / experimental value of the evaporation rate are shown in Figure 2. Figure 10(d), and the data in Tables 1-3 above, it can be seen that the calculation formula proposed in this application fits the experimental data well, with errors less than 10%. Therefore, it is believed that the design scheme generation method for the geocomposite layer proposed in this application can provide a relatively reliable calculation basis for selecting the design values ​​of the important parameters of the geotechnical materials in each layer of the geocomposite layer according to actual on-site working conditions and project requirements, thereby improving the lifespan and safety of the roadbed project.

[0233] An embodiment of the present application further provides a computer-readable storage medium having a computer program or instructions stored thereon. When the computer program or instructions are executed by a processor, the above-mentioned method for generating a design solution for a geocomposite layer is implemented.

[0234] The embodiment of the present application further provides a computer program, which, when executed, is used to implement the above-mentioned method for generating a design solution for a geocomposite layer.

[0235] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0236] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, a feature specified as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of this application, "N" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0237] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, fragment or portion of code comprising one or N executable instructions for implementing a custom logical function or process step, and the scope of the preferred embodiments of the present application includes alternative implementations in which functions may be performed in a different order than shown or discussed, including performing functions in a substantially simultaneous manner or in a reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0238] It should be understood that various parts of the present application can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, the steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement the method: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array, a field programmable gate array, etc.

[0239] A person skilled in the art may understand that all or part of the steps carried out in the method for implementing the above-mentioned embodiment may be completed by instructing the relevant hardware through a program, and the above-mentioned program may be stored in a computer-readable storage medium, which, when executed, includes one of the steps of the method embodiment or a combination thereof.

[0240] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A roadbed soil humidity automatic control system, characterized in that: include: A geocomposite layer, wherein the geocomposite layer comprises first to third composite layers, the first composite layer absorbs moisture from the roadbed soil, the second composite layer discharges moisture from the roadbed soil, and the third composite layer blocks underground capillary water; Collection component, used to collect roadbed soil humidity and external environment humidity; The control component performs humidity control operation on the geocomposite layer according to the humidity of the subgrade soil and the humidity of the external environment, so as to control the geocomposite layer to absorb or discharge moisture from the subgrade soil.

2. The automatic control system for roadbed soil moisture according to claim 1, characterized in that: The first composite layer is a gradient porosity wicking fiber geotextile layer, the second composite layer is a three-dimensional composite geonet layer, and the third composite layer is a geotextile layer.

3. The automatic control system for roadbed soil moisture according to claim 2, characterized in that: The geocomposite layer is laid horizontally along the roadbed as a whole, with both end portions directly exposed to the external environment or attached to the inner walls of the drainage ditches on both sides of the road shoulders. The pore equivalent aperture of the first composite layer is linearly proportional to the contact distance of the upper surface of the second composite layer. The pore equivalent aperture of the first composite layer close to both sides of the road shoulders is larger than the preset aperture. The second composite layer includes longitudinally arranged ribs in the middle and cross-arranged ribs in the upper and lower parts. The rigidity of the longitudinally arranged ribs in the middle is greater than the rigidity of the cross-arranged ribs in the upper and lower parts. The upper and lower surfaces of the second composite layer are covered with a third composite layer.

4. The automatic control system for roadbed soil moisture according to claim 1, characterized in that: The control assembly includes a ventilation device, a power output device, and a controller, wherein the controller controls the ventilation device and the power output device to perform the humidity control operation.

5. The automatic control system for roadbed soil moisture according to claim 4, characterized in that: The ventilation device includes a ventilation pipe, a vertical riser and a guide spiral wind hood, wherein the ventilation pipe is symmetrically laid on the roadbed soil near the road shoulder, the pipe body of the ventilation pipe is arranged in the first composite layer and the second composite layer, the pipe wall of the ventilation pipe is provided with wind holes distributed in a spiral shape, the vertical riser is connected to the horizontal ventilation pipe and is arranged perpendicular to the horizontal ventilation pipe, and the guide spiral wind hood consists of guide blades and a top cap and is installed on the top of the vertical riser.

6. The automatic control system for roadbed soil moisture according to claim 4, characterized in that: The power output device includes an energy supply device, a pump case and an electric valve, wherein the energy supply device supplies energy to the pump case, and the electric valve controls the ventilation speed of the pump case.

7. A method for generating a design scheme for a geocomposite layer, characterized in that: The method is used to generate a design scheme for a geocomposite layer in the roadbed soil moisture automatic control system according to any one of claims 1 to 6, wherein the method comprises the following steps: Obtaining the environmental working conditions of the roadbed soil, wherein the environmental working conditions include the roadbed soil being in a saturated or unsaturated state, the roadbed soil being in an oversaturated state, and the capillary phenomenon of the roadbed soil; The absorption-diffusion-evaporation coupling efficiency of the first composite layer is calculated based on whether the subgrade soil is in a saturated or unsaturated state, the drainage rate of the second composite layer is calculated based on whether the subgrade soil is in an oversaturated state, and the blocking efficiency of the third composite layer is calculated based on the capillary phenomenon of the subgrade soil; The parameter range of the corresponding composite layer is determined according to the absorption-diffusion-evaporation coupling efficiency, the drainage rate and the blocking efficiency, and a design scheme of the geocomposite layer is generated according to the road engineering requirements and the parameter range.

8. The method for generating a design scheme for a geocomposite layer according to claim 7, wherein: The calculation formula of the absorption-diffusion-evaporation coupling efficiency is: Among them, (ET) f is the absorption-diffusion-evaporation coupling rate, is the actual net radiation, G is the soil heat flux, ρ air is the air density, C p is the specific heat of air at constant pressure, e s is the temperature T air The saturated water vapor pressure of the air, e s is the temperature T air The actual water vapor pressure of the air at that time, is the equivalent aerodynamic impedance, λ is the latent heat of water vaporization, Δ is the slope of the saturated water vapor pressure curve, γ is the dry and wet constant, is the equivalent surface impedance, K ec is the absorption-diffusion-evaporation coupling coefficient; The calculation formula of the drainage rate is: in, is the drainage rate of the second composite layer, θ K is the hydraulic conductivity of the three-dimensional composite geonet, δ is the total thickness of the three-dimensional composite geonet, W is the longitudinal width of the geonet, δ1 and δ2 are the thickness of the main reinforcement and the secondary reinforcement respectively, s is the spacing of the equal-diameter reinforcements, is the included angle of the top projection of the primary and secondary reinforcement, θ net is the contact angle between the rib material and the transmission liquid infiltration interface, K P is the external load correction factor, K η is the material wettability correction factor; The calculation formula of the blocking efficiency is: Among them, η f is the blocking efficiency of the second composite layer, h 0-gd is the theoretical rising height of underground capillary water, h gd is the actual rising height of underground capillary water, θ net is the contact angle between the reinforcement material and the underground capillary water infiltration interface, f1 is the retardation correction constant, and δ is the actual thickness of the geonet.

9. A computer-readable storage medium having a computer program or instruction stored thereon, characterized in that: When the computer program or instruction is executed, the method for generating a design scheme for a geocomposite layer according to any one of claims 7 to 8 is implemented.

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed, the method for generating a design scheme for a geocomposite layer according to any one of claims 7 to 8 is implemented.

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